Method for the production of polyamide nanocomposites, corresponding packaging materials and moulded bodies

ABSTRACT

The invention relates to a method for the production of polyamide nanocomposites made from base polymers comprising aromatic components and organically-modified phyllosilicates in a double-screw extruder with a front-feeder and a side-feeder. Said method is characterised in that a portion (A) from 8 to 15 wt. % of a granulate of the base polymer is introduced in the front-feeder of the double-screw extruder and the main portion (B) of said granulate of the base polymer is introduced by means of the side feeder of the double-screw extruder and that 2 to 8 wt. % of the modified phyllosilicate is introduced into the melt of the granulate portion (A) of the base polymer, whereby the wt. % proportions relate to the finished polyamide nanocomposite. According to the invention, packaging materials with high UV absorption and improved gas and aroma barrier effect can be produced by said method. Furthermore, the corresponding packagings the use thereof and moulded bodies produced by means of said method are disclosed.

The present invention relates to a method for the production ofpolyamide nanocomposites made from polyamides and phyllosilicatesaccording to the preamble of claim 1. Polyamide nanocomposites producedaccording to the present method in accordance with the invention can beused for producing transparent packaging means, especially packagingmeans with high UV absorption, as well as improved gas and aroma barriereffect. Moreover, the polyamide nanocomposites produced in accordancewith the invention further offer the possibility of producing mouldedbodies, hollow bodies, semi-finished products, plates, tubes, etc., evensuch of larger thickness or wall thickness.

In the field of plastic, nanocomposites materials are understood aspolymer formulations which comprise finely dispersed phyllosilicatessuch as clay minerals within the polymer matrix. The relevant aspect isthat the phyllosilicates are exfoliated up to the individual layers,i.e. they are split up and then dispersed. The properties of suchnanocomposites have already been published in numerous patentspecifications and specialised publications. It is known that finelydispersed clay minerals or phyllosilicates provide the composite withimproved properties such as increased mechanical strength, improvedbarrier properties against oxygen and carbon dioxide, among otherthings. The improvement of the properties of a polymer matrix by meansof finely dispersed clay materials has already been described in closerdetail in the patents U.S. Pat. Nos. 4,739,007 and 4,810,734 forexample.

Nanocomposites have also already entered the packaging sector. Theexfoliated clay minerals ensure in packaging films an inhibiteddiffusion of gas molecules such as oxygen, carbon dioxide or aromaticsthrough the packaging material.

Polyamides have been established for many years as preferredthermoplastic polymeric materials in the packaging field. One of themain reasons is the property profile of this class of materials such asfavourable barrier effect against oxygen and carbon dioxide as well asthe outstanding mechanical properties of the packaging foils made ofpolyamide. When using aliphatic polyamides as a matrix for nanocompositematerials, a reduction in the transparency can be observed because thesenanocomposite filling materials are capable of increasing thecrystallisation of the aliphatic polyamides, which on the other hand canstrongly impair the transparency of such products.

A desirable goal in the packaging field is the polyamide nanocompositeas a part of multiple-layer films in combination with other polymerssuch as polyolefines. Multiple-layer films which are composed ofdifferent types of polymers with mutual adverse adhesion can be rigidlyconnected with each other by suitable bonding layers. Suchmultiple-layer films can be used to produce a large variety of packagingproducts such as containers, bottles, bags, thermomouldable products,tubes, etc. The products can be provided with a dyed, light-permeable ortransparent configuration. In order to enable the successful marketingof a large variety of products, the presentation of these productstowards the customer plays an increasingly important role. To allow thecustomers to see what is contained in a packaging, the transparency isof decisive importance. Numerous suitable barrier materials consist ofaliphatic polymers. Such compounds usually crystallise during thecooling process and lead to packaging materials with reducedtransparency. The reduction of the transparency by the crystallisationprocess can be remedied by using amorphous, partially aromaticpolyamides.

The durability of packaged perishable foodstuffs and other products isdefined predominantly by the oxygen barrier of a packaging. The UVbarrier also plays a decisive role in numerous other packagingapplications because UV rays are able to damage sensitive foodstuffs(like oxygen). When storing sensitive foodstuffs such as meat in thecold shelves of major distributors, they are often subjected to damagingUV radiation because many of the employed light sources also radiatelight in the UV spectrum.

Special expensive UV absorbers such as Tinuvin® 234, a hydroxyl phenylbenzotriazole UV absorber produced by Ciba Specialty Chemicals Inc.,Basel, Switzerland, can be introduced into the materials which representcomponents of said multiple-layer composites. Since these UV absorberscan migrate under application conditions, the use of these compoundsoften requires an additional layer to the multiple-layer composite inorder to prevent the migration of the UV absorbers into the packagedproduct or into the atmosphere. The addition of an additional layer tothe multiple-layer film is not possible in all cases because the numberof producible layers is defined by the configuration of the filmextrusion systems.

The packaging of especially perishable foodstuffs with a furtherextended durability cannot easily be solved by the packaging systems andadditives currently available on the market. Especially the enabling ofa combination of all of the following listed properties in a singlepackaging requires further improvements. Such properties are:

-   -   Highly transparent packaging    -   High mechanical strengths    -   Extremely high gas barrier effect against oxygen and carbon        dioxide    -   High aroma barrier effect    -   High UV protection    -   Additionally extended durability in cold shelves    -   Official approval as foodstuff packaging

The invention is therefore based on the object of providing a method forproducing polyamide nanocomposites with which, among other things, it ispossible to produce transparent and clear packaging materials orpackaging means with high mechanical properties, a high barrier effectagainst oxygen and carbon dioxide and which simultaneously also offer anincreased protection against UV radiation.

With respect to a method for the production of polyamide nanocomposites,this object is achieved according to the features of the independentclaim 1. With respect to a packaging means with high UV absorption aswell as improved gas and aroma barrier effect, this object is achievedaccording to the features of claim 13. Additional inventive features areobtained from the dependent claims.

In accordance with the invention, polyamide nanocomposite materials areproduced by admixing an organically-modified phyllosilicate in acompounding process by means of a double-screw extruder (e.g. a “WP ZSK25” of Werner & Pfleiderer). For the tests performed in connection withthe present invention, the following screw geometries were used bytaking the percentage number of screw elements per screw area intoaccount: Employed screw geometries (Table 1): Screw D Screw E Screw FScrew Screw Screw region region region Worm elements K L M K L M K L MConveyor elements 86 40 85 53 100 72 70 50 70 Left conveyor elements —20  4  7 — — — — — (retarding) Kneading blocks 14 20  7 20 —  8 24 —  9Kneading blocks (not — — — 20 — — — — — conveying) Kneading blocks (left— 20  4 — —  3  6 —  3 conveying) Mixing elements (left — — — — —  6 —17  6 conveying) Spacing disks 1 mm — — — — — 11 — 23 12Legend on Table 1:Screw regions:K Front-feeder up to dosing of modified layer mineralL Dosing of modified layer mineral up to side feederM Side feeder up to die

In the case of screw D, the dosing of the modified layer mineral intothe melt is not possible.

In order to determine the film quote (FN), a flat film is extruded fromthe granulate, e.g. with a “Plasti-Corder” of Brabender Co. For a periodof 20 minutes the film is moved past an optical system which detects theimpurities in the film, counts them (stated in m2) and determines theirsize. Such an optical system with an evaluation programme is sold by OCSGmbH Witten under the name of “Folientest FT4” (Film Test FT4).

The impurities are subdivided into 10 size classes (cf. Table 2). Theseclasses are weighted with different weighting factors. TABLE 2 Sizeclass Weight factor [μm] (fi) <100 0.1 100-200 1 200-300 10 300-400 20400-500 30 500-600 40 600-700 55 700-800 100 800-900 200 >900 350

The film quote is calculated according to the following formula byadding the sum totals of the weighted impurities per size class and bydivision by 1000. $\begin{matrix}{{FN} = \frac{\sum\limits_{i = 1}^{10}\quad{{xi} \cdot {fi}}}{1000}} & (1)\end{matrix}$

The following applies: xi=Impurities/m2/size class

-   -   fi=Weight factors

Phyllosilicates within the terms of the invention are understood as 1:1as well as 2:1 phyllosilicates. In such systems, layers of SiO₄tetrahedrons are regularly linked with such made of M(O,OH)₆octahedrons. M stands for metal ions such as Al, Mg, Fe. In 1:1phyllosilicates one tetrahedron layer and an octahedron layer are linkedwith each other. Examples are kaolin and serpentine minerals.

In the case of 2:1 three-layer silicates, two tetrahedron layers areeach combined with one octahedron layer. If not all octahedron placesare occupied with cations of the required charge for compensating thenegative charge of the SiO₄ tetrahedrons and the hydroxide ions, chargedlayers will occur. This negative charge is compensated by the insertionof monovalent cations such as potassium, sodium or lithium or bivalentcations such as calcium in the space between the layers. Examples for2:1 phyllosilicates are French chalk, mica, vermiculite, illites andbentonites, with the bentonites, which include montmorillonite andhectorite among others, being easily swellable with water as a result oftheir layer charge. Moreover, cations are easily accessible for exchangeprocesses.

The layer thicknesses of the phyllosilicates are usually 0.5 nm to 2.0nm prior to swelling, especially preferably 0.8 nm to 1.5 nm (distanceof the upper edge of the layer to the next following upper edge of thelayer). It is possible to further increase the layer distance, such thatthe phyllosilicate is converted with polyamide monomers (swelling), e.g.at temperatures of 25° C. to 300° C., preferably 80° C. to 280° C. andespecially 80° C. to 160° C. over a dwell time of usually 5 to 120minutes, preferably 10 to 60 minutes. Depending on the dwell time andthe type of the chosen monomer, the layer distance will additionallyincrease by 1 nm to 15 nm, preferably 1 nm to 5 nm. The length of theplatelets is usually up to 800 nm, preferably up to 400 nm. Any existingor constituting pre-polymers usually also contribute to the swelling ofthe phyllosilicates.

The swellable phyllosilicates are characterised by their ion exchangecapacity CEC (meq/g) and their layer distance d_(L). Typical values forCEC are at 0.7 to 0.8 meq/g. The layer distance in a dry, untreatedmontmorillonite is at 1 nm and increases by swelling with water orapplication with organic compounds to values up to 5 nm.

Examples for cations which can be used for exchange reactions areammonium salts of primary amines with at least six carbon atoms such ashexanamine, decanamine, dodecanamine, stearylamine, hydrogenated fattyacid amines or even quarternary ammonium compounds such as ammoniumsalts of α-,ω- amino acids with at least six carbon atoms.

Suitable anions are chlorides, sulphates or even phosphates. In additionto ammonium salts, it is also possible to use sulphonium or phosphoniumsalts such as tetraphenyl or tetrabutyl phosphonium halogenides.

Since polymers and minerals have very different surface tensions,bonding agents can also be used in accordance with the invention fortreating the minerals in addition to the cation exchange. Titanates oreven hydrosilicons such as γ-aminopropyl triethoxysilane.

The invention will now be explained in closer detail by reference to thefollowing examples and results:

As examples in accordance with the invention, two polyamidenanocomposite formulations were produced with additions oforganically-modified phyllosilicates of 5 wt. % and 8 wt. %. Anamorphous, partly aromatic copolyamide 6I/6T (isophthalicacid/terephthalic acid=2/1) was used as a polyamide matrix which isobtainable on the market under the name Grivory G21 of EMS-CHEMIE AG.

As a comparative example a PA 6 which is obtainable on the market underthe name “Grilon F 40 NL” of EMS-CHEMIE AG was produced with 5 wt. % ofmodified phyllosilicate. The production of the polyamide nanocompositeswas made by the addition of specially modified phyllosilicate.

In accordance with the invention, it is now possible, as alreadydescribed above, to use phyllosilicates which were modified with oniumions. Such modified phyllosilicates can be obtained on the market fromseveral firms such as Sudchemie (D), Southern Clay Products (USA),Nanocor (USA), CO-OP (J). The modified phyllosilicates used for thecomparative examples and examples in accordance with the inventionconcern montmorillonite treated with quarternary ammonium ions. Theligands of the nitrogen are methyl, hydroxyethyl and hydrogenated tallowor non-hydrogenated tallow.

The compounded materials was thereafter granulated and dried for 24hours in vacuum at 90° C. The compounded polyamide phyllosilicatematerials were processed on a casting film unit of Dr. Collin GmbH,extruder type “3300 D30x25D”, take-off type “136/350” into films in thefollowing manner. The granulates were molten in a conventionalsingle-screw, three-heat-zone extruder with a temperature profile of250° C. to 260° C. The melt was drawn off through a sheet die with a diegap of 0.5 mm directly onto a cooling roller with a take-off speed of 8m per minute and with a set temperature of 130° C.

Films with a thickness of approximately 50 μm are produced with theabove setup:

No phyllosilicates were added in the comparative examples I (aliphaticpolyamide) and III (partly aromatic polyamide). Examples IV and Vrepresent a combination in accordance with the invention of partlyaromatic polyamide and phyllosilicates. Comparative example I PA 6“Grilon F40 NL” Comparative example II PA 6 +5 wt. % of phyllosilicateComparative example III PA 6I/6T “Grivory G21” Inventive example IV PA6I/6T +5 wt. % of phyllosilicate Inventive example V PA 6I/6T +8 wt. %of phyllosilicate

The following measurements were performed on the materials of thecomparative examples and the films produced according to the inventiveexamples:

The oxygen transmission rate (OTR) was measured by means of the Moconmeasuring instrument of type “Oxtrans 100” at 23° C. and at 0% relativehumidity and at 85% relative humidity (“r.h.”; cf. Table 3).

The UV absorption values were determined by means of a Perkin-ElmerLambda “15 UV/VIS” spectrophotometer. The measurements were performed ina wavelength region of 200 nm to 400 nm. The recording of the lighttransmission occurred in the measured wavelength region on a scalebetween 0% and 100%. The evaluation in the improvement of the UV barrierwas made by comparing the surfaces under the absorption curves ofdifferent films, with comparative example III, which only containedGrivory G21 without phyllosilicate addition, being set as 100.

In addition, the light transmission was also determined in the visiblewavelength region of 550 nm, leading to an indication of thetransparency of the film. The established values are compiled in Table 3below. TABLE 3 % transmission of Oxygen permeability UV in comparisoncm3/m2 day bar cm3/m2 day bar with Grivory G21 at 23° C./0% r.h. 23°C./85% r.h. 200 to 400 nm Light at 550 nm Comparative 25 70 63 70example I Comparative 12 30 55 65 example II Comparative 30 10 100 92example III Example IV 14 5 79 85 Example V 13 4 63 82

As is shown by the measurement results of the two examples IV and V inaccordance with the invention, these films show strongly improved valuesrelating to oxygen diffusion and UV absorption as compared with thecomparative examples. The relatively good values as shown in Table 3under the comparative examples I and II for UV absorptions of PA 6 filmsamples can be explained with a reduced transparency relative to the6I/6T variants. The measurement of the light transmission values at 550nm clearly show this reduced light transmitting capacity.

The employed polyamides containing aromatic groups also come with afavourable UV barrier effect, although these polyamides also have a hightransparency. The addition of a phyllosilicate to these specialpolyamides further increases the favourable UV barrier withoutsubstantially impairing the excellent transparency of these products.

The following tables compare exemplary parameters of the method inaccordance with the invention with parameters of the comparativeexamples: Base polymer A (Table 4): Modified phyllosilicate Dosing pointfor Quantity Throughput Vacuum Film Test No. base polymer A Type [wt. %]Dosing point [kg/h] [mbar] Screw grade Comp. ex. 1 Front-feeder G 5Front-feeder 10 150 D * Comp. ex. 2 Front-feeder G 5 SF 15 150 D * Comp.ex. 3 Front-feeder G 5 MB 20 150 D * Comp. ex. 4 Front-feeder + SF G 5Front-feeder 20 150 D * Comp. ex. 5 Front-feeder + SF G 5 Front-feeder20 150 E 9.19 Example 1 Front-feeder + SF G 5 Melt 20 150 E 0.67 Example2 Front-feeder + SF H 4.5 Melt 20 150 E 0.21 Example 3 Front-feeder + SFG 5 Melt 20 50 F 1.80 Example 4 Front-feeder + SF H 4.5 Melt 20 50 F0.80

PA 6I/6T was used each time as base polymer. The change to another screwimproved the film quality in comparative example 5 to such an extentthat a film degree can be determined. A film degree of around 10 isinsufficient however. A strong improvement in the film degree isachieved only by a combination of all measures in accordance with theinvention (cf. examples 1 to 4). Base polymer B (Table 5): Modifiedphyllosilicate Dosing point for Quantity Throughput Vacuum Film Test No.base polymer B Type [wt. %] Dosing point [kg/h] [mbar] Screw grade Comp.ex. 6 Front-feeder G 5 SF 15 150 D * Comp. ex. 7 Front-feeder + SF G 5Front-feeder 20 150 D ** Comp. ex. 8 Front-feeder + SF G 5 Front-feeder20 150 E 11.62 Example 5 Front-feeder + SF G 5 Melt 20 150 E 0.37Example 6 Front-feeder + SF H 4.5 Melt 20 150 E 0.62 Example 7Front-feeder + SF G 5 Melt 20 50 F 1.43

PA 6/PA 6I/6T Blend was used in each case as base polymer B. In thecomparative example 7, the split-up of the base polymer B into two partsand the dosing of the same at different places already leads to animprovement in the film quality. The determination of a film degree isonly enabled when also the screw geometry is changed. A very strongimprovement in the film degree is achieved only by the combination ofall measures in accordance with the invention (cf. examples 5 to 7).Base polymer C (Table 6): Modified phyllosilicate Dosing point forQuantity Dosing Throughput Vacuum Film Test No. base polymer C Type [wt.%] point [kg/h] [mbar] Screw grade Comp. ex. 9 Front-feeder G 5Front-feeder 10 150 D * Comp. ex. 10 Front-feeder G 5 SF 15 150 D *Comp. ex. 11 Front-feeder + SF G 5 Front-feeder 20 150 D ** Comp. ex. 12Front-feeder + SF G 5 Front-feeder 20 150 E 21.02 Example 8Front-feeder + SF H 4.5 Melt 20 150 E 3.40 Example 9 Front-feeder + SF G5 Melt 20 50 F 4.40 Example 10 Front-feeder + SF G 3.2 Melt 20 50 F 5.61

PA MXD6/MXDI was used in each case as base polymer C. As a result of thesplit-up of the base polymer into two parts and the dosing of the sameat different locations of the extruder, an improvement in the filmquality is achieved in comparative example 11 as well. The determinationof a film degree is also only enabled when the screw geometry ischanged. Depending on the employed phyllosilicate, a strong improvementin the film degree is achieved only through a renewed change in thescrew geometry and the combination of all measures in accordance withthe invention (cf. examples 8 to 10).

Legend in connection with Tables 4 to 6:

SF: Side-feeder

-   MB: Masterbatch: 1^(st) extrusion: Production of MB (ratio    granulate: mod. phyllosilicate is approx. 70/30). Both in    front-feeder.    -   2^(nd) extrusion: Incorporation of MB in residual granulate.        Both in front-feeder.-   Mod. Phyllosilicate: G Montmorillonite, modification; quarternary    ammonium compound with methyl, bis-hydroxyethyl, hydrogenated    tallow;    -   H Montmorillonite, modification; quarternary ammonium compound        with methyl, bis-hydroxyethyl, tallow;-   Screws: D Dosing of the modified phyllosilicate in the melt not    possible;    -   E No favourable mixing effect between phyllosilicate addition        and side-feeder;    -   F Favourable mixing effect between phyllosilicate addition and        side feeder;-   Film degree: * Very bad film quality: Determination of the film    degree not possible.    -   ** Bad film quality: Determination of the film degree not        possible.

It was surprisingly noticed that the base film quality was obtained whena small part A (preferably 8 to 15 wt. %, especially preferably 10 to 12wt. %) of the granulate of the base polymer is dosed in thefront-feeder, but that the main part B is added at a later time via aside-feeder. The modified phyllosilicate (preferably 2 to 8 wt. %, morepreferably 2 to 5 wt. %, especially preferably 2.5 to 5 wt. %) is dosedinto the melt of the granulate portion A, preferably without using aside-feeder, simply by gravity. All data in wt. % relate to the sumtotal of the recipe components of 100 wt. %.

The extrusion parameters (low temperature profile, high speed, highthroughput) and the screw geometry are preferably chosen in such a waythat a high shearing is achieved. The speed of the screw is preferablymore than 200 revolutions per minute (rpm). More preferably the speed is300 rpm, and especially preferably the speed is 400 rpm.

The screw geometry is also relevant. It is necessary to ensure afavourable melting of the granulate portion A, e.g. by kneading blocks,before the phyllosilicate is added. After its addition and before theside-feeder it is necessary to provide a favourable mixing effect again.After the side-feeder it is necessary to provide a sufficient kneadingand mixing effect. Measures which increase the dwell time also have apositive effect on the result, but should not lead to an excessivedegradation of the base polymers. The employed screw geometries aresummarised in Table 1. Moreover, the screw should preferably beconfigured in such a manner that for the purpose of degassing theapplication of vacuum before the die is enabled. A pressure or vacuum ofless than 200 mbars is preferable; a pressure or vacuum of less than 50mbars is especially preferable.

A high throughput is also preferable. A throughput of 20 kg/h incombination with these recipes constitutes the maximum amount possiblefor the employed double-screw extruder (WP ZSK 25). Generally,operations should be conducted in the upper quarter of the throughputand speed range of the employed extruder, preferably at the upperthroughput and speed limit. The throughput limit is determined by themaximum possible torque at the desired low temperatures.

The temperatures set on the extruder must be chosen rather low relatingto the melting point and the melt viscosity of the polymer. Temperaturesare preferable which are 10° C. to 20° C. lower than in theincorporation of other filling materials. In the case of amorphous basepolymers, 10° C. to 40° C. are mostly suitable, preferably temperatureswhich are 20° C. to 40° C. lower (relating to the entire T-profile onthe extruder) than usual.

The following temperature profile was set for the processing of PA6I/6T, PA 6/PA 6I/6T—Blends and PA MXD6/MXDI: Front-feeder 10° C.,rising temperatures from 220° C. to 240° C., die temperature 240° C.Operations were conducted at a screw speed of 400 rpm.

The polyamide nanocomposites produced in accordance with the inventioncan be processed with conventional plastic processing methods intodifferent articles, e.g. films, tubes, bags, bottles and containers.They can be produced either by monoextrusion or coextrusion methods.Suitable plastic processing methods are blow or cast film methods,extrusion blow moulding methods, transfer stretch-blow moulding,injection blow moulding, pipe extrusion methods and laminate methods.

Moreover, the use of the method in accordance with the invention forproducing polyamide nanocomposites offers the possibility of producingmoulded bodies, hollow bodies, semi-finished products, plates, pipes,etc. even with larger wall thicknesses. Preferred processing methodswhich are generally known comprise injection moulding, internal gaspressure, and profile extrusion methods as well as blow moulding bymeans of standard extrusion, 3D extrusion and vacuum blow mouldingmethods. Moulded bodies include for example radiator tubes, coolingwater containers, compensating reservoirs and tubes and containersguiding other media (especially media with higher temperatures) as areused in the production of means of transport such as cars, airplanes,ships, etc.

The packaging articles can be arranged as a single-layer ormultiple-layer packaging. In the case of multi-layer packaging, thepolyamide nanocomposite material can be used as outside layer,intermediate layer or also as innermost layer in direct contact with theproduct.

A further embodiment of the invention also relates to the combination ofsaid polyamide nanocomposites in combination with a multi-layercomposite. The barrier effect of this layer is further improved by usingphyllosilicates in a barrier layer. This allows reducing the layerthickness of the barrier layer for achieving a certain required barriereffect. Since the barrier material in multi-layer composites mostlyrepresents the most expensive component of the packaging, the entirepackaging system can thus be made cheaper. A further possibility forreducing the costs for the packaging is the outstanding UV barriereffect of the partly aromatic polyamide nanocomposites. The use of theexpensive, special organic UV absorbers can be reduced or entirelyeliminated by using these polymer formulations, thus avoiding furthercosts for the required packaging system. Organic UV absorbers are alsosubject to a certain migration, which may lead to problems concerningthe foodstuff suitability of packaging materials.

Examples for possible applications of the present invention in thepackaging field, without any limiting effect for the scope of validityof the invention, are packagings for semi-finished products and productssuch as foodstuffs, meat products, cheese and milk products,toothpastes, cosmetic products, beverages, paint, varnishes ordetergents. Such packagings include toothpaste tubes, tubes for cosmeticproducts and foodstuffs, packagings for cosmetic products, body care,detergents, beverages, foodstuffs, etc.

Surprisingly, it was found that complex packaging problems can be solvedby choosing special polyamides which are used as matrix polyamides andby special compounding methods. Potential polyamides are such whichcontain aromatic components. Suitable polyamides of this type cancontain PA 6I/6T, PA 6/PA 6I/6T blends or co-polyamides produced fromHMDA and/or MXDA and aliphatic and/or aromatic dicarboxylic acids.Moreover, the processing in accordance with the invention of polyamidesbased on lactams (lactam-6, -11, -12) or other polymers is possible.

Packaging produced by using the method in accordance with the inventionoffer extended durability to especially to perishable packaged goodswhich are sensitive to the permeability of packaging covers towardsgases, especially oxygen and carbon dioxide. Such packaging also showsan improved barrier effect against spices and flavours such as distilledoils. The packaging also show an unexpected reduction in thetransmission of UV light.

1. A method for the production of a polyamide nanocomposite made from atleast one base polymer and an organically-modified phyllosilicate in adouble-screw extruder with a front-feeder and a side-feeder, wherein aportion (A) of from 8 to 15 wt. % of a granulate of a base polymer basedon 100% by weight of the nanocomposite, is introduced in a dosed mannerin the front-feeder of the double-screw extruder, and a main portion (B)of said granulate of the base polymer is introduced through theside-feeder of the double-screw extruder, and wherein 2 to 8 wt. % basedon a total of 100% by weight of the nanocomposite, of theorganically-modified phyllosilicate is introduced in a dosed manner intothe melt of the granulate portion (A) of the base polymer.
 2. The methodaccording to claim 1, wherein said portion (A) comprises 10 to 12 wt. %of the granulate of the base polymer, and wherein theorganically-modified phyllosilicate comprises 2 to 5 wt % based in eachcase on the total of 100 wt. % of said nanocomposite.
 3. The methodaccording to claim 1, wherein the organically-modified phyllosilicate isintroduced in a dosed manner by gravity and without the use of aside-feeder into the melt of the granulate portion (A).
 4. The methodaccording to claim 1, wherein an E or F extruder screw is used.
 5. Themethod according to claim 1, wherein the melt of the polyamidenanocomposite is subjected to a pressure of less than 200 mbar withinthe double-screw extruder.
 6. The method according to claim 1, whereinthe base polymer comprises at least one aromatic component.
 7. Themethod according to claim 1, wherein the base polymer comprises apolymer made from at last one component selected from the groupconsisting of HMDA, MXDA, aliphatic and aromatic dicarboxylic acids. 8.The method according to claim 1, wherein the base polymer comprises atlest one polymer made from a lactam.
 9. The method according to claim 1,wherein the base polymer comprises PA 6, PA 6I/6T or PA 6/PA 6I/6Tblends or PA MXD6/MXDI.
 10. The method according to claim 9, wherein anamorphous, partly aromatic co-polyamide PA 6I/6T is used as basepolymer.
 11. The method according to claim 1, wherein modifiedthree-layer silicates are used as organically-modified phyllosilicate.12. A method for the production of a transparent packaging material withhigh UV absorption and with improved gas and aroma barrier effect, whichcomprises the method according to claim 1, wherein a packaging film,preform or pipe is extruded from said extruder.
 13. A packaging materialwith high UV absorption and improved gas and aroma barrier effect whichis produced with a method that comprises the production of polyamidenanocomposites made of base polymers containing aromatic components andof organically-modified phyllosilicates in a double-screw extruder witha front-feeder and a side-feeder, characterized in that for theproduction of the polyamide nanocomposite a portion (A) of from 8 to 15wt. % of a granulate of a base polymer based on 100% by weight of thenanocomposite, is introduced in a dosed manner in the front-feeder ofthe double-screw extruder, and a main portion (B) of said granulate ofthe base polymer is introduced through the side-feeder of thedouble-screw extruder, and wherein 2 to 8 wt. % of the modifiedphyllosilicate based on a total of 100% by weight of the nanocomposite,is introduced into the melt of the granulate portion (A) of the basepolymer.
 14. The packaging material of claim 13, which comprises asingle-layer or multiple-layer structure.
 15. The packaging material ofclaim 14, wherein the polyamide nanocomposite forms an outside layer,intermediate layer or innermost layer, with the innermost layer beingconfigured for direct contact with the product to be packaged.
 16. Apackaging article, characterized in that it comprises a packagingmaterial according to claim 13 in form of a film, bag, bottle, tube orpipe.
 17. A method of using a packaging material according to claim 13for packaging semi-finished goods and products selected from the groupcomprising of foodstuffs, meat products, cheese and milk products,toothpaste, cosmetic products, beverages, paint, varnish and detergents.18. A method for producing a product selected from the group comprisingof a moulded body, a hollow body, a semi-finished product, a plate, anda pipe, according to claim 1, wherein said product is formed from or ofan extrudate from said extruder.
 19. A moulded body which is producedwith a method that comprises the production of polyamide nanocompositesfrom base polymers and organically-modified phyllosilicates in adouble-screw extruder with a front-feeder and a side-feeder,characterized in that for the production of the polyamide nanocompositea portion (A) of from 8 to 15 wt. % of a granulate of a base polymerbased on 100% by weight of the nanocomposite, is introduced in a dosedmanner in the front-feeder of the double-screw extruder, and a mainportion (B) of said granulate of the base polymer is introduced throughthe side-feeder of the double-screw extruder, and wherein 2 to 8 wt. %based on a total of 100% by weight of the nanocomposite, of the modifiedphyllosilicate is introduced in a dosed manner into the melt of thegranulate portion (A) of the base polymer.
 20. The moulded body of claim19, wherein the base polymer contains an aromatic component or is madeof a lactam.
 21. A method of using a packaging article according toclaim 16 for packaging a product selected from the group comprising ofsemi-finished goods, foodstuffs, meat products, cheese, milk products,toothpaste, cosmetic products, beverages, paint, varnish and detergents.22. A packaging article, characterized in that it comprises a packagingmaterial according to claim 15 in form of a film, bag, bottle, tube orpipe.
 23. A method of using a packaging material according to claim 15for packaging a product selected from the group comprising ofsemi-finished goods, foodstuffs, meat products, cheese, milk products,toothpaste, cosmetic products, beverages, paint, varnish and detergents.24. A method of using a packaging article according to claim 22 forpackaging a product selected from the group comprising of semi-finishedgoods, foodstuffs, meat products, cheese, milk products, toothpaste,cosmetic products, beverages, paint, varnish and detergent.